A very reasonable stance -- congratulations on getting lucky (unless it was the result of tons of research) and picking Mithril after jumping from Backbone (+Marionette I assume). There were
a lot of wrong, but good-looking choices to make there.
In case it wasn't clear, I still think Vue is the best minimal component library all things considered -- simple syntax, simple and mostly clear usage, support for typescript, not too much overbearing tooling (they're trying to "fix" this with vue-cli though), and a large community & ecosystem. I'm just scared they're going to blow it and start putting in , but I'm well aware I'm just a hanger-on to the project (I don't contribute to it).
Mithril[0], on the other hand is almost allergic to change, in the linux kernel way, which is great until you have a problem with how it works or think it should work differently. Mithril is also the most complete though -- it has routing, AJAX, all that stuff built in (context: normally when people say "vue/react" they mean "vue/react + vue/react-router + vuex/flux"). I also particularly like how Mithril uses the hyperscript syntax and just calls it a day -- full "single file components" without the transpilation hassle. Mithril also passes one of the key indicators for high quality software, a comparisons page[1].
Shameless plug -- I wrote a short guide[2] on how to get started with mithril & parcelJS (ignore the link URL, I started with rollup and then quit because it was too inconvenient to use, I write about it in Step 5):
[0]: https://mithril.js.org/
[1]: https://mithril.js.org/framework-comparison.html
[2]: https://vadosware.io/post/mithril-systemjs-and-rollup-gettin...